Nasal passages are the airways located inside the nose that allow air to enter and exit the respiratory system. They are lined with a mucous membrane that helps filter, warm, and humidify the air before it reaches the lungs. The nasal passages also contain tiny hair-like structures called cilia, which help trap dust and other particles. These passages connect to the sinuses, which are air-filled spaces in the skull that also play a role in filtering air. Proper functioning of the nasal passages is essential for breathing and can be affected by conditions like allergies or sinus infections.